Shulou(Shulou.com)11/24 Report--

PART.01 what is grounding? As we all know, lightning will produce instantaneous high voltage and strong current, once hit the ground without lightning protection equipment, it is bound to cause significant damage. Therefore, the communication equipment with a large number of semiconductor devices must be protected against lightning.

Communication equipment usually uses the method of "equipotential connection" to protect against lightning. The so-called "equipotential connection" is popularly called "grounding", and "grounding" is to connect the equipment to the earth.

By grounding the equipment against lightning, the lightning can be released to the earth before the lightning enters the equipment, so as to achieve the purpose of lightning protection.

Communication equipment in addition to lightning grounding, there are several other grounding methods, which will be described in detail below.

What are the types of PART.02 grounding? There are mainly three kinds of grounding in communication equipment: lightning protection grounding, working grounding and protection grounding.

Lightning protection grounding: a method of connecting input or output power cables to the earth through lightning arrester. The lightning arrester is actually a kind of varistor, which can be turned on instantly and become a conductor at a high voltage. Therefore, lightning protection can be effective by installing the lightning arrester in the input / output line of the equipment and connecting it to the ground wire.

Work grounding: it refers to a kind of grounding in order to ensure that the power system and electrical equipment meet the normal working requirements, and the positive grounding is used in DC communication equipment.

Protective grounding: the metal shell of electrical equipment may be electrified due to insulation damage. In order to prevent this voltage from endangering personal safety, the equipment metal shell needs to be grounded. This kind of grounding is called protective grounding.

In life, there are many places to use grounding devices, such as large household appliances, such as refrigerators, air conditioners, etc., the wire plugs used are three-core. Under normal circumstances, the general municipal electricity appliances as long as there are two zero wires and two hot wires can work, like this three-core one more than the ordinary power cord is used for grounding, that is, the ground wire. According to the common sense of electricity consumption, it is generally distinguished by the left zero line, the right fire line and the ground wire in the middle.

In addition to daily life, grounding also plays an important role in communication bureaus (stations). It is not only related to the safety of equipment and maintenance personnel, but also directly affects the quality of communication.

With the maturity of lightning protection grounding technology, people gradually realize that lightning protection and grounding is a systematic project, so how to better effective lightning protection?

As a result, joint grounding was born.

PART.03 what is joint grounding? Joint grounding is to make the basic grounding bodies and other special grounding objects of each building in the communication bureau (station) connect with each other to form a common land network. and the lightning protection grounding, working grounding and protection grounding of electrical equipment share a group of grounding system.

As shown in the following figure, when a strong lightning current flows into the earth, the potential of the earth immediately rises, because all the ground wires are connected, the ground potential of the communication equipment rises with the earth, and there is no potential difference between the earth and the earth. The equipment will not be damaged by lightning strikes back.

The joint grounding in the following figure connects the work site, lightning protection ground, and protective ground together, with-48 V DC supplying DC power.

It should be noted that the connector of the joint grounding grid should be network-like distribution, it is best to form a three-dimensional network, in order to have the function of voltage equalization and allelism. The grounding body must be made into a good equipotential body. The lightning protection grounding row, the protective grounding bar and the working grounding bar can be connected with the grounding body at different points to meet the requirements of joint grounding.

The application of PART.04 joint grounding system is shown in the following figure, which is the joint grounding scheme of a certain computer room. In order to form an equipotential surface in the computer room on the same floor, a special grounding row is arranged around each floor, which is connected with the shell of power equipment on the same floor, which is conducive to the protection of lightning overvoltage to protect the safety of personnel and equipment.

This is the end of the introduction of joint grounding. Finally, what are the advantages of joint grounding system?

The advantage of PART.05 combined grounding system eliminates the potential difference that endangers the equipment, and can make the potential between the line systems in the same layer and the potential between the earth roughly equal. The common grounding bus (the connecting wire that connects the current or voltage to the grounding grid, or the conductor that connects the grounding electrode into one) establishes a reference zero point for the whole world. When the ground potential rises, the ground potential rises everywhere, and there is basically no potential difference at any time.

The interference of the ground wire system is eliminated. A variety of ground wire systems are usually designed according to different electrical characteristics, which influence each other. Now, after using a joint grounding system, the ground wire system is interference-free.

Good electromagnetic compatibility. Due to the equipotential of strong, high-frequency and low-frequency electricity, and the use of sub-shielding equipment and branch ground wire, the performance of electromagnetic compatibility is improved.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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